1. Field of the Inventions
The present inventions relate to power transmitting apparatuses, such as vehicle transmissions, which transmit power from an engine of a vehicle to the wheels of the vehicle and which are configured to properly select transmission of power and cutting-off of power to or from the wheels.
2. Description of the Related Art
Two types of known power transmitting apparatuses for vehicles (e.g., “automatic transmissions”) provide starting power (power for initiating movement of the vehicle from a stop) in different ways. One type uses a torque converter (“torque converter type”) and another type uses a starting clutch (“starting clutch type”) to provide starting power used to start the movement of the vehicle from a stop. In the torque converter type devices, the starting performance benefits from the torque amplifying function of the torque converter. On the other hand, the starting clutch type benefits from increased efficiency because this type of system does not continuously lose power through slippage which occurs in the torque converter types e.g. during a steady running of vehicle.
Japanese Laid-open Patent Publication No. 3193/2005 discloses a power transmitting apparatus which is a torque converter type automatic transmission combined with a lock-up clutch. In this transmission, the lock-up clutch has a clutch piston connected to a turbine of a torque converter and is movable between a connected position in which it abuts against the inner circumferential surface of a torque converter cover and a non-connected separated position. Thus, the torque converter cover and the turbine can be directly connected and disconnected via the clutch piston.
Japanese Laid-open Patent Publication No. 227565/2003 discloses a power transmitting apparatus of the torque converter type having an idle-stop function for automatically stopping an engine when a vehicle is stopped. This power transmitting apparatus comprises an oil pump driven by power from the engine to supply a clutch mechanism and the torque converter with oil to actuate them and additionally comprises an electrically-driven oil pump to supply the clutch mechanism and the torque converter with oil when the engine is restarted after being in an idle-stopped condition.